Art of producing aluminum nitrid.



|Vl. BARNETT (Y1 L. BURGESS.A

ART 0F PRODUCINGALUMNUM NITRID.

APPLICATION F1LED1U11E1, 1917.

1,252,649. 12119111911 Jan. 8, 1918.

A y uw l ful improvements in the rt of Producing,"-

Aluminum Nitricl, of which tlieifolioufing is a speeiication, referencebeing had therein to the a'ccornpirnying drawing. v

This invention or discovery relates to the 'art of producing aluminumnitricl and lies 1 furnace.

for its Cbject the production of this substance :it iess expense than isinvolved in trie production thereot by processes ieretofore in use. lnpractising the present in- -Vention or iliscoyery aluminum carbid istreated Wi'tli nitrogen gas :it a temperature above 900 C. and below20000 C., but preierabiy between'900O C. and 1:92000 C. in which rangeof temperatures conversion 01" tiie aluminum ceriiici into aluminumnitriet taires place.

The metlfzoii er manufacturing aluminum nitricl heretofore and etpresent in use consists in passing nitrogen, 'or producer ges. overmixture of carbon :and neuite, pn.- yiously celcinecl,4 iieutecl toabout i800o C. er 19000 C. ,e revolving 'electric resistance Themanipulation ot sucfn e resistance furnace, operating et these hightemperatures, is n metter or" difcuity, as is als@ the preservation cithe lining ei the il nece. The nitrid so produced is e, grey/ish pcwfierwhich can be converteoi into sodium aluminate and. ammonia by treatmentwith sociium liyclroxid oniy by prolonged boiling, pref ernblyin aneutociave. Furtliferninre, in the manufacture of aiurninuin nitriciunder tile processes heretofore .m new employed, the nigh temperature:trequentiy ieads to reiersel of reaction. The Working' tempera.-tures'must be carefully Wetehef and meineinecl winin certain limits,otherwise the prciuct detained contains iittle nitrogen and is difiicuitto decompose.

the nienutecture ofeiuniinnni nitricl 'by our new precess Seremirnarlred :Hivernage-s are secured. En the first place, the alunnin numnutriti is produced at a. moderate teniperature. Again, the manufactureof aluminum nitri. at moderate temperatures tends to increase the lifeof the furnace linings. Furthermore,l en account of the relatively lowtemperatures employeii. in our process there is ne danger of reversalv4ci reactie n.. 0F SEE, Y.

the eiuininum nitrid mafie 1- b: tre:

i ,suitable acids und elimlis even ena vic-us ci' tive be used fornitrirl our Qrocess.

Referring to Fig. l, l2 denotes :i furnace -..f,iicli nay be of ironwith a suitable refractory 'lining7 such as iileoricir. lrVithin the .funace l2 is a retort 1% cf any suitable i, clay, and within ui iunicarbid to be treated :viii be piaceri u nich retort it Wiii besubjecteei 'te tinev aerien of nitrogen gas which may, be introducedinto the retorty by pipes 15 ernbiy pro ed with vulves i@ by wiiiel j ofnit-regen tu tie chain" ci rt may* be regulated. Air and moisture beeiciuced ircm the retort` es fer une. The furnace. und retortrney iceany suitable manner, as by means rg, as et burners 1Q, er by n exteriorto the furnace A ort lllis prefernioiy proyifle. et its n L withcharging iiop r .i8 goronli u inombie cover fit the bothe retort i4there is preferabiy previcierl :i ningefl Licor 33., the lining of whichi-e''-"ictory material, and which door cned clownwarciiy when tliealumiric.. 1,Tf1-minced in the retort, to be reniorer'. The hinged door33 may ieli closed ny a spring catch The nitrogen gas inlet pipes l5 mayail be connecter to e manifold i3 which communicates with the source ofthe nitrogen. Between the source oi'E the nitrogen und the i .eniioid i3there will nretferably be l meter i by which the e pi; to a staclror r,.niney. enti snicl furnace muy be supporteri by any suite is. es bycoinmns or by un uren,

' n n Mier forni of apparatus 'which i'n'iy be A in tile prociuction ofif i nur shown in iterring to Q, denotes the we l ie tw'nucc and 24 thecomminuteci :iluminun'z: eerliici Within the furnace chamber. 25 denotesholders for the resisance eienent Q6 which may consist ci: carbon or g1carbon. the seid resistance boitiers prei'erebly eurronneleci lijfwete-r glee mounted in the furnace Walls. The Water jackets 27 Will, inpractice, be provided with inlet and outlet pipes 28 so that acirculation of Water may be maintained in said jackets forth purpose ofpreventing the resistance holdei from becoming over-heated. Theresistance holders 25 are preferably formed hollow or tubular, as shown,so that the re sistance element may be more readily insertedtand also topermit the resistance clement to be knocked out at the end of anoperation. Electrically connected with the resistance holders, by meansof attached parts 29 and 30, are suitable conductors 31 by which acurrent of electricity, either di reet or alternating, may be caused topass.

t will be understood that any suitable furnace, mayl be employed incarrying on our process and that the apparatus'shown in Figs. land 2represents only two forms of equipment by which our invention may becarried into effect.

1n practising our invention With the apparatus shown in lig. 1 We takealuminum carbid and grind same to about 20 mesh.

lVe. introduce this through the hopper 18 into the retort 14. Heat'lsthen applied to the retort 14 and when the aluminum carbid contained inthe retort has been brought ,to a temperature of preferably from 9000'C. t'o 12000 C. nitrogen gas is introduced into the retort through thepipes 15./ WhenI the meter 17 shows that nitrogen gas is no longer beingabsorbed by the aluminum carbid, the operation may be stopped by cuttingoff the source of heat and allowing the furnace to cool down. y When/the aluminum nitrid which has been produced in retort .14 has cooleddown it may be removed through the hinged door 1n practising ourinvention with the apparatus shown in Fig. 2 the furnace 24 is filledwith aluminum carbid, ground to about 20 mesh through openings 43 in thetop of the furnace, which openings (after the furnace has been charged)may be closed by plugs or otherwise. Electric current of suitablestrength is than passed through the resistance element 2G the currentbeing maintained at such strength that the charge of aluminum carbid isheated preferably between 900o C. and 1200o C. When the charge ofaluminum carbid has been brought to the -described temperature nitrogengas is passed into the chamber of the furnace by means of' tures.

pipes 44 preferably provided With valves 45 by which the flow ofnitrogen gas tothe chamber of the furnace may be regulated.

After the reaction begins the current is`so the furnace charge, theoperation may be stopped by cutting olf the electric current. After thefurnace ycharge has cooled the Walls of the furnace 24 maybe partly,re-f' moved from the charge and the Aaluminum nitrid Will be foundwithin in a more or less compact mass. In practice We have found thataluminum carbid containingtraces of silicon, titanium and iron, or anyof them, either free or in the form, of earbids, vWill combine withnitrogen with exceptional ease,

The aluminum carbid employed in this process is preferably that made inaccordl ance with the process covered vby our U. S. Patent No.1,222,593, dated April 17, 1917, as carbid made in accordance with saidpatn ent may be successfully treated. in the pro'- duction of aluminumnitrid at the relatively I low temperatures hereinbefore. set forth, and

insuch treatment will absorb "from 17% Ato 22% of its Weight ofnti-ogen.

Having thus described our invention or discovery We claim and desire tosecure by Letters Patent:

1. The herein described process for producing aluminum nitrid,consisting intreating aluminum carbid with nitro'en g s atl temperaturesof from about 900 to about 1200o C.

2.- The herein described processifor `pro-` ducing aluminum nitrid,consisting in intro ducing nitrogen gas into a retort containingaluminum carbid which has been heated and maintained at a temperature offrom about 900 C. to about 1200"- C., cutting. off the supply of heat,cooling the charge and re,- moving the aluminum nitrid produced..

, In testimony whereof We affix our signa- MAURICE -BARNETT LouisBimenes.

